Annual Water Yield PAWC Raster

Science, Research & Data
1

Hello, Community! Hope everyone is well during this time of crisis!
I have a question regarding the PAWC raster of the Annual Water Yield Model. I have data for soils of my state in Brazil, for which I actually had to use pedotransfer functions, and I managed to obtain PAWC per soil layer. How do I proceed now? Do I calculate a weighted average dividing by soil depth?

Thanks! Take care!

2

Hi @Victor_Maluf,

I’ll let others respond here but I did want to point to a prior post that might be useful: Annual Water yield model calibration. Further down @swolny links to some resources that might prove helpful.

Best,

Doug

3

Thank you, @dcdenu4!

4

Hi @Victor_Maluf -

Just to verify, when you say “per soil layer”, do you mean layers at different depths (also called horizons)?

If your values are in mm/m, then yes, you should divide the PAWC value for each layer by that layer’s soil depth (in mm) to get the AWC fraction. Then you can combine these layers into a single value by doing a weighted average based on their depth. This is definitely a simplification, and I’d be interested to hear if others do it differently.

~ Stacie

5

Hi, @swolny! Yes, “soil layer” also means “soil horizons”. My AWC is already in fraction. I’m looking at your “how to” material and it’s really helpfull! I found that the solution of using the weighted average is, so far, the best one. I also thought about using the higher value of AWC from soil horizons, or even the most common value. Maybe ignoring outlyers (too high or too low AWC values) is also a good idea.

Thanks @swolny and @dcdenu4! Take care!

6

Hello to every one. I am quite doubtful on how to proceed with PAWC. I have soil data from a national grid (250 m resolution) which covers these soil characteristics:
pH, soil organic carbon content, bulk density, coarse fragments content, sand content, silt content, clay content, cation exchange capacity (CEC), total nitrogen as well as soil organic carbon density and soil organic carbon stock.
I wonder if there is an automated way to calculate PAWC from these data. I understand that the SPAW tool can do that for specific points, however I’ve got a grid with thousands of points and using SPAW is unthinkable. I would like to include the whole data in my area and so obtain a detailed PAWC map. Is there any function or tool in GIS that cab do this calculation in a raster?